How does display:none, left:-9999px, visibility: hidden, z-index affect SEO?

Question

css

Colleagues!
Please help anyone with experience. Faced the following problem. When redesigning the site, we decided to place a large amount of content compactly, using the techniques of hiding blocks like display: none in tabs, accordions and other amenities so that the user does not scroll through a long sheet, but can switch content in parts. However, all content should be indexed as before. SEO is very important to us. Google gives mixed answers in various forums about how all this affects SEO. We are very afraid of lowering positions because of this.
Advise what is better in terms of SEO and user experience: left:-9999px, visibility: hidden, change z-index or something else?
Thanks in advance for your replies.

Answer 1

Doesn't matter, these are all rumors. Unless you can get a filter for the text and background of the same color, as an attempt to deceive the search engine.
I also used to worry about this, but the essence is simple: do not try to deceive the search engines and everything will be fine. If what you do is for the convenience of users, then there will be nothing to worry about.

Answer 2

display:none - you can
left:-9999px, - you can
visibility: hidden - it's better to refuse
z-index - you can
Basically robots take text from the page ignoring css, a lot of sites in the top use dynamic blocks with display:none, just don't shove spam there text

Answer 3

The main rule is that the content should be readable for the user and not be spam text to "catch" search queries.
I take out the 10 under the main text in the form of tags separated by commas.